Spark plug



c. SCHMIDT S PARK PLUG Filed Sept. 21, 1925 Patented Dec. 16, 1924.

UNITED STATES PATENT OFFICE.

CHARLES SCHMIDT, OF McKEES ROCKS, PENNSYLVANIA, ASSIGNOB OF ONE-HALF TO ABRAM GOLDV'ARG.

SPARK PLUG.

Application filed September 21, 1923. Serial No. 664,052.

To all whom it may concern.

Be it known that 1, CHARLES SCHMIDT, a citizen of the United States, residing at McKees Rocks, State of Pennsylvania, have invented new and useful Spark Plugs, of

which the following is a specification.

The present invention relates to an improved spark-plug of the type ordinarily used in internal combustion engines.

It is well known that such spark plugs are constantly getting out of order by reason of the electrodes losing their proper spaced relation either by expansion under excessive heat, or becoming bent, distorted 1 or broken through ordinary handling or by accidentally hitting or dropping the plug.

There is also difliculty and expense involved in properly securing the cathode to the jacket or barrel of the plugs.

The object of the present invention is the provision of a spark-plug which will overcome the above-stated drawbacks and which will admit of rough handling and use under extraordinary conditions without the sparking points becoming broken, improperly spaced, bent or distorted.

It is a further object of the invention to provide a spark plug which can be easily cleaned, manufactured at a minimum of cost compared with those now on the market, and which is extremely durable.

The invention resides in the sundry details of construction, combination and arrangement of parts hereinafter more fully described and pointed out in the appended claim.

In this specification and the annexed drawings, the invention is disclosed in the form in which it is considered to be the best, but the invention is not limited to such form because it is capable of being embodied in other forms; and it is to be understood that in and by the claim following the description herein it is intended to cover the invention in whatever form it may embody within the scope thereof.

In the drawings which illustrate the preferred embodiments of the invention as at present devised:

Figure 1 is a side elevation of the plug.

Fig. 2 is a longitudinal sectional view of the plug, taken substantially on line 2-2 of Fig. 1.

Fig. 3 is a top plan view of Fig. 1.

F 4 is a bottom view of Fig. 2, and

F igs. 5, 6 and 7 are views similar to Figure 4, and illustrating modified constructlons of cathode electrodes on the jacket or barrel.

F ig. 8 is a further modified view of the inventlon.

Figs. 9 and 10 illustrate further modifications of the invention.

The spark plug comprises the usual hollow metallic barrel or jacket 1, having one end exteriorly threaded as at a and its upper end formed with a polygonal enlar ement 1), to receive a wrench to enable t e plug to be inserted tightly into the head of an engine cylinder and removed therefrom. The jacket or barrel 1 is preferably made of hardened steel or other suitable substantial metal. The interior of the jacket is formed with a circumferential shoulder 2 upon which a corresponding shoulder 3 of the insulating block 4 rests. The block 4 is of the ,usual construction and is assembled in the jacket 1 in the usual manner, there being a lock nut 5 which slidably fits over the outer face of the insulating block 4 and threadedly engages the inner face of the upper end of the jacket 1, as at 6, the nut also engaging a shoulder 7 on the insulating block to force the same down upon the shoulder 2 and to tightly clamp the same in assembled osition.

In the present plug, a gas et 8 is interposed between the shoulder 2 and the insulating block 4 so as to form a gastight joint at this point. a

The plug 4 has a longitudinal bore 9 therein extending throughout its length, in which is slidably received, in close-fitting relation preferably, the upper end of the electrode 10. This anode electrode 10 is of substantial thickness or diameter and preferably of a non-malleable metal, so that it is not susceptible to breaking, distortion or other injuries which may occur from rough handling of the plug, such as by dropping the same, carrying the same loosely in the tool box, or the like. The electrode is formed intermediate its ends with an enlarged abutment 11, which will engage with the lower end of the insulating block 4 to limit the upward movement of the electrode in the in sulating block 4, when it is assembled in position therein and tightly drawn up by theclampi'ng nut 12, which is threaded on the upper end of the electrode and binds against the upper end of the insulating block. In order to insure gastight joints between the electrode and the insulating block, suitable gaskets are interposed such as' at 13 and 15. The lower end of the electrode 10 extends downwardly to a point in the vicinity of, or preferably slightly below, the lower extremity of the plug jacket 1 and is centrally arranged with respect to the longitudinal axis of the jacket.

The cathode electrode of the spark plug is provided by forming the same integrally with the jacket, and from the same stock as composes the jacket. This can be'accomplished by suitable milling operation. This cathode electrode is indicated in the drawing at 16, and extends inwardly from the lower edge of the jacket toward the lower end of the electrode 10 but spaced from the latter to form a suitable spark gap 17. The electrode 16 is of substantial thickness and width, and in the drawings tapers to a point so that the electrical current can be concentrated in the gap.

The jacket 1 is cut away at its lower end as at 18, for a distance substantially the thickness of the electrode 16, and circumferentially of the edge for about half the circumference thereof, as clearly indicated in Figs. 1, 2 and 4, this cut-away portion lying opposite the electrode 16. The purpose of this cut away portion is to facilitate the cleaning of the plug when necessity requires.

Fig. 5 shows a modification of the cathode electrode 16, in that in this modification there are two electrodes provided diametrically opposite each other, and formed integral with and from the stock of the jacket 1. These electrodes are indicated as 16 and 16", the lower edge of the jacket being cut away 011 both sides of each of the electrodes, as indicated at 18 and 18*.

In Fig. 6 substantially the same type of electrode is shown, except the electrode 16, instead of being a tapered spur extending toward the anode electrode 10, it consists of an inwardly extending tongue lying to one side of the electrode 10. The lower edge of the jacket 1 is cut away at 18 similarly as shown in Figs. 2 and 4.

In Fig. 7, the electrode 16 consists of an inwardly extending tongue having a perforation or aperture in one end thereof, through which the lower end of the anode electrode 10 may extend or be suitably arranged above the same with respect to the edges of the aperture 19, the lower extremity of the electrode 10 being suitably spaced from the edge of the aperture 19 to provide the proper spark gap. In this embodiment, the lower end of the spark plug is cut away at 18- similarly as shown in Figs. 2 and 4.

In all of the embodiments of this invention, the cathode electrode lies flush with the lower end of the jacket or barrel of the spark plug, and consists of a relatively broad pro jection of non-bendable material, thus elimi- I nating spark plug troubles usually experienced by the cathode -and anode electrodes becoming improperly spaced, distorted or broken.

Having thus described the invention, it will be obvious that a very practical, durable and inexpensive spark plug has been provided.

Fig. 8 shows a modified form of the spark plug which is in all respects the same as the plug shown in Figs. 1 to 4 inclusive, but wherein the cut-away portion 18 has been eliminated or not provided.

In Fig. 9 is shown a further modification wherein the cathode electrode 16 is extended at an angle of 45 relative to the lower edge of the jacket 1 either in an upward or downward direction. In this embodiment 1 electrode 16 is of the same shape as that shown in Figs. 1 to 4 inclusive.

In the embodiment shown in Fig. 10 the cathode electrode 16 is similar to the one shown in Fi s. 1 to 4 inclusive and 8, except that it 1s arranged endwise and of a 9 right-angle triangular formation, and the hypothenuse of which tapers upwardly to the wall of the shell or jacket l and its straight edge lies flush with the lower edge of the latter. In this form of the invention 100 the electrode does not restrict the open end of the shell or jacket 1 as much as in the other forms and thereby facilitates the cleaning of oil and carbon from within the interior of the shell.

Having thus described the inventon in the forms in which it is at present devised, what is claimed as new and upon which Letters Patent are rayed, is:

A spark plug opened at its lower end, an anode electrode within the jacket and insulated therefrom, a cathode electrode integral with the jacket and extending inwardly toward said anode electrode to form a spark gap, and lying 115 substantially flush with the lower edge of said jacket, the lower edge of said jacket opposite said electrode being cut away for a distance about its periphery.

In testimony whereof I have hereunto set 126 my hand.

CHARLES SCHMIDT.

aving a metal jacket 

